Currently, commercially available computer tomography (CT) imaging systems are typically equipped with densely installed detector cells along predetermined directions. A detector cell means an individual sensor of a two-dimensional array of detectors or detector elements. The detector elements are adjacently installed on a predetermined surface. CT-scanners are geometrically as efficient as possible in closely placing a full complement of the detectors.
Due to the full complement of dense detector elements, currently available CT imaging systems are expensive. The high costs are substantially due to the above described a large number of detector cells along the channel directions. In addition, an equally large number of necessary electronics units associated with the detector cells also contributes to the expensive costs of these imaging systems. The high costs are even more critical using photon counting detectors rather than integrating detectors. In general, regardless of a detector type, the denser the detector cells are, the more expensive the imaging system becomes. In general, finely pitched detectors of the standard design dramatically increase the hardware costs.
Due to the densely packed integrating detector elements, currently available CT imaging systems also suffer from some undesirable cross-talk effects. Because of proximity of the adjacent detector elements, X-ray arriving at the detectors are scattered across and over the adjacent detector elements. The densely packed detector elements generally make the scattering correction difficult to achieve a desirable result in reconstructing an artifact-free image.
In this regard, most of currently practiced reconstruction methods in CT also assume the full complement of densely packed detector channels. These reconstruction methods include filtered backprojection, backprojection filtering and some forms of iterative reconstruction.
In view of the above discussed prior art issues, a practical solution is still desired for a method and a system for reconstructing an image without substantially affecting image quality based upon projection data that is acquired from detectors having a sparse direction so as to ultimately reduce the high costs of the detector elements and the associated electronics in the standard CT systems.